I would have thought the problem was with the PC rather than the Devolo plug:
a) Does it work reliably if it is the only computer pluged in to the Devolo?
b) Does it work reliably if it is plugged directly into one of the router's LAN ports?
Surface Pro 5 News - release date, UK price, features, specs
Gear VR vs. Daydream: Which delivers the best VR experience?
Best Mac antivirus 2017
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.